Hans-Georg Maassen is an unlikely dissident. In his trademark three-piece suits and small glasses, he looks more like a law professor. Indeed, that is what he studied, earning a doctorate on the legal status of asylum seekers in international law.

This bourgeois exterior is the perfect cover for a man who was Germany’s top spy, charged with protecting the country from the far-right and Islamists. But now he is no longer under the quiet protection of the German state; he is its victim. He is under investigation from the agency he once led, the Federal Office for the Protection of the Constitution (BfV).

Like George Smiley, Maassen is a remnant of an older and more powerful country, soldiering on in spite of the decline, trying to preserve what he can. That someone who was once at the heart of the Establishment in the 1990s now finds himself an outcast is symbolic of how much Germany has changed. The cracks in the postwar political consensus have become impossible to ignore.

On his website – Die Akte Maassen – he documents his battle with the BfV, publishing in full all the documents that he has forced the government to release about his case. ‘It’s like mail from the madhouse,’ he tells me.